1: You just had a heated discussion with someone. Disagreement, lies, bad habits, pick your poison. You keep thinking "Why is (s)he acting like this? If I had reacted in X way instead of Y. How is (s)he going to behave when we meet again? How am I?". Independently of whether what cause the argument was justified or not, your mind keeps spending an increidble amount of time and energy reliving it, playing different scenarios, imagining reasons on your and his(her) behavior. It consumes you. It keeps playing in your head.
2: You have a headache. You take a pill, it doesn't go away. You go to the Internets, and find a myriad of potential reasons for your headache. You take an appointment with a doctor, it's friday next week. Your headache comes and goes, and you start (again) creating scenarios: did I hit my head? Might this be hereditary? Am I feeling pain elsewhere? When did it actually start? And thanks to everything you read off the Internet, you start drawing pretty scary conclusions: Might be migraine. Brain injury. Or something more serious.
3. You're feeling overweight. You've been eating bad lately, you reckon. It starts showing around the waist. You stop wearing tight stuff so it doesn't show, while you work it out. You become more sensitive of fat jokes. You stop yourself from ordering the large french fries, as it will go straight to your hips. Off your mind goes: You start losing a little bit of confidence, as you don't feel sexy. Every time someone mentions anything related to weight, you think they're talking about you. You look outside at all the skinny people, you feel envy, you feel frustrated.
Pain is real and unavoidable. Suffering, on the other hand, is completely made up.
Your and your loved ones will always disagree and fight. That brings pain. All the stories and recreations in your head afterwards? That's suffering. A pure product of your imagination, useless and negative.
That pain in your head is coming from somewhere in there, a palpable root. All the paranoia and hypochondria? Suffering, sponsored by your imagination.
The added fat on your body is there. You can (sadly) feel it. All the extra sensitiveness and and frustration? Suffering, straight out of nowhere and ready to bring you down.
Your mind is capable of the most awesome things. And also, some of the worst. Again, pain is inevitable and unavoidable, is part of life. Suffering, on the other hand, is product of our imagination. Our mind. Our number one enemy.